As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREATED FROM FORWARD DISCREPANCY. PLEASE REFERENCE AML 397685, WHEN AIRCRAFT WAS BEING REPOSITIONED FROM TERMINAL TO HANGAR FOR MX, APU WAS STARTED AND AS SOON AS THE APU GENERATOR WAS SELECTED ON A POPPING AND HISSING NOISES WERE HEARD FROM BEHIND AND A FIRE WAS OBSERVED NEAR THE OBSERVERS 02 MASK. FLIGHT 5804 - FILED OPEN THIS IS CURRENTLY A WORK IN PROGRESS.